Ultraviolet light is emitted by the sun, carbon arc lamps, mercury vapor lamps, tungsten lamps and other light sources. The ultraviolet portion of the spectrum is from about 180 to about 390 nm. Ultraviolet light having a wavelength within this range is capable of degrading synthetic resins or polymers presently used to manufacture structures, or coatings commonly exposed to ultraviolet light, e.g., sidings, paints, or varnishes.
It is estimated that over 40% of all plastics in the United States need some protection from ultraviolet radiation. A polymeric matrix can be photochemically broken down causing discoloration, cracking, embrittlement and peeling. Ultraviolet photodegradation can result in the loss of optical, physical, and mechanical properties of the original polymer.
There is a need for improved ultraviolet absorbers because some presently available ultraviolet absorbers are subject to ultraviolet degradation themselves, i.e. they are not stable as ultraviolet absorbers for long periods of time when incorporated in a carrier.